Unknown prepaid account

Hi everyone! I have to ask a kind of personal question, so please keep it classy. No one knows my background, I just need practical answers. 

My husand and I received two emails from T-Mobile instructing us to renew our prepaid account. However, I thought the prepaid account was closed three months previous. I tried to log in to the prepaid website using both the email and the prepaid number, but was unable. I called and the rep told me in no uncertain terms, that if we received the emails, there was a prepaid account still active using the email account, but no using the number of which I was aware. Naturally this is unsettling. Secret phones are no bueno, so I want to make sure when I inquire about this, I'm not being the ***hole. Is anyone aware of any other scenario that could possibly explain the emails? And remember, please be nice.